1. Field of the Invention
The present invention relates generally to a decorative bulb unit, and more particularly to a decorative bulb unit with a filament shunt member mounted in the bulb socket thereof.
2. Description of the Prior Art
Decorative light strings are commonly used in celebrations and festivals. The light string usually comprises a number of bulb sockets connected in series to an electric wire. Bulbs, usually incandescent ones, are mounted to the bulb sockets for connection with the wires. When a single bulb fails to illuminate, the whole string fails to light. It is very time-consuming to locate and replace the defective bulb. Thus, light strings with shunt circuits for overcoming the problems are known, such as U.S. Pat. Nos. 6,084,357 and 6,323,597 B1. These conventional designs of shunt circuits, however, require a shunt member to be encased in the bulb itself or are made with expensive electrical elements. The manufacturing process is also complicated.
Thus, it is desired to have a shunt circuit for a light string to alleviate the problem.
A primary object of the present invention is to provide a decorative bulb unit with a filament shunt member. The shunt member is mounted in the bulb socket of the decorative bulb unit and electrically connected with the filament of the bulb in parallel.
The other object of the present invention is to provide a fight string having a shunt circuit for each bulb of the light string to avoid defective bulbs causing malfunction of the whole light string. The shunt member having a simple structure and low costs of material and manufacturing.
Another object of the present invention is to provide a light string comprising a shunt circuit for each bulb, the shunt circuit being formed easily with a simplified manufacturing process.
A further object of the present invention is to provide a shunt circuit for a light string, the shunt circuit being operative with regular bulbs whereby costs are reduced.
To achieve the above objects, in accordance with the present invention, there is provided a light string comprising electrical wires to which a number of bulb sockets are connected in series. Each bulb socket defines a receptacle for receiving and retaining a bulb with the bulb in electrical connection with the electrical wires. A shunt circuit is incorporated in the socket, including a shunt member made of alumina. The shunt member is removably disposed in the receptacle of the socket, independent of the bulb, for being electrically connected to the electrical wires in parallel with the bulb whereby when the bulb burns out, the shunt member maintains the current flowing through the wires. The shunt member may further include an insulation sheath surrounding the alumina section.